In fact, no NFL running back, elite or otherwise, has rushed for 100 yards against the 49ers in the past 25 games, a streak that goes back to Nov. 22, 2009, when Green Bay’s Ryan Grant had 129 yards against San Francisco in the Packers’ 30-24 win.

It’s the NFL’s longest streak (the Bears are second at 12 games), but it will be tested Sunday when San Francisco visits Philadelphia, home of a potent rushing attack headlined by running back LeSean McCoy.

The Eagles rank second in the league in rushing (182 yards per game) and McCoy (115 yards per game) is runner-up to Oakland’s Darren McFadden (131) in rushing after recording two games of 120-plus yards.

Linebacker Patrick Willis said the streak is a point of pride and has allowed the Niners to make opposing offenses more predictable.

“Any time you have something going on, a streak or whatever it may be, you want to keep that thing alive,” Willis said. “But at the end of the day we just know if you can keep a team from running the ball and make them throw, you’re taking away one element of the game.”

After San Francisco’s front seven was retooled in the offseason, there were questions about whether it would remain the same stout unit that limited opponents to 3.5 yards a carry, the second-best mark in the NFL.

A pair of well-respected, experienced run-stuffers, nose guard Aubrayo Franklin and inside linebacker Takeo Spikes, signed elsewhere as free agents after the lockout. To fill those spots, the Niners shifted 330-pounder Isaac Sopoaga from defensive end to nose guard, where he spent his first four NFL seasons. Spikes’ spot was occupied by NaVorro Bowman, who was more of a question mark after an inconsistent rookie season.

So far, the transition has been seamless. And Bowman’s emergence is a reason why the Niners’ rush defense ranks third in the NFL, and San Francisco and Chicago are the only teams yet to allow a rushing touchdown this season.

Bowman, a third-round pick in 2010, is tied for fourth in the NFL in tackles (30) after posting a career-high 13 in last week’s 13-8 win at Cincinnati.

Bowman possesses more sideline-to-sideline speed than Spikes, which could be particularly useful in containing Philadelphia quarterback Michael Vick, who had 97 yards in a season-opening win against St. Louis and is averaging 6.4 yards a carry.

Vick gives the Eagles a second player capable of breaking the Niners’ 100-yard streak.

But Bowman gives San Francisco an inside linebacker similar in style to Willis, arguably the best at his position in the league.

“That’s a good point,” Niners coach Jim Harbaugh said when asked if it was sometimes hard to tell Willis and Bowman apart on the field. “Yeah, there have been times when you see them running, making a play outside of the box, or physically coming up and take on a lineman, or a back and protection. They’re very similar. They’re very good. They’re very athletic. They’re very tough and they make similar plays.”

Where they rank

49ers defense: Third overall against the run at 62.7 yards per game; league-best 2.9 yards per carry

Eagles offense: Second overall (to Raiders) at 182 yards per game rushing; fourth at 5.4 yards per carry.